Images produced by printers, fax machines and other marking devices are ubiquitous in the industrialized world. Users of marking devices have come to expect high image quality. Hence, poor quality images, containing undesirable artifacts, often result in a waste of worker productivity and media resources and could even result in the miscommunication of important information. Therefore, one metric for determining the business value of a printer, for example, as well as of other types of marking devices, is dependent upon the printer's imaging quality.
A conventional printing system is illustrated in FIG. 1, wherein the printing system includes an image output terminal 200 and a raster image processing engine 100. The raster image processing engine 100 receives image data 10 (an image file, a portable document format file, electronic document, or other electronic form of data containing data to be printed by the image output terminal 200).
The raster image processing engine 100 includes a rasterizer 110 that rasterizes the image data 10 before storing the processed image data in memory 120. The rasterizer 110 may perform portable document language interpretation, trapping, and/or anti-aliasing. The stored processed image data is processed by a post rasterizer 130. The post rasterizer 130 may perform calibration and/or tone-response-curve adjustment.
The raster image processing engine 100 also includes a port or ports to allow the user to input test image data (300 and 400) for calibration or diagnostic purposes. Moreover, the port or ports allow the user to sample (not shown) the processed test image data to determine the quality of the raster image processing engine 100 and the various components of the raster image processing engine 100.
Upon being processed by the raster image processing engine 100, the processed image data is, for example, binarized by image binarizer 210 of the image output terminal 200. It is noted that for purposes of describing the conventional printing system, the print engine is a binary printer, namely the depth resolution of a pixel is one bit.
The image binarizer 210 prepares the image data so that the image data is printer dependent and at the proper resolution for rendering by the marking engine of the image output terminal 200. Thereafter, a register image module 220 makes any final adjustments to the image data with respect to registration and converts the image data into appropriate signals to be utilized by the imager 230. The imager 230 may be a laser for a xerographic printer or a printhead for ink printer.
The conventional image output terminal 200 also allows the user to input test image data (500) for calibration or diagnostic purposes. However, the user cannot, conventionally, sample the processed test image data from image binarizer 210 to determine the quality of the image binarizer 210. The best that a user can do, conventionally, is to look at a test print, which may not provide enough distinguishable information to isolate the source of the problem within an image output terminal.
More specifically, image quality problems within an image output terminal can be caused either from failures in the marking engine or in the binarization of the image data. Many of these problems render indistinguishable artifacts, thereby making it very difficult to determine root cause (source) of the artifact.
In other words, the hardware or software utilized in the printing system may fail, causing the marking engine to produce undesirable artifacts on the printed medium. Although the cause of the failure may be malfunction of one of the different processes or components, each failure may produce the same undesirable artifact on the printed medium. Thus, the user of the printer may recognize a failure, but the artifact will not provide enough information to the user so as to determine the point of failure.
As noted above, a conventional printing system provides some diagnostic capabilities with respect to isolating problems in the raster image processing engine. However, if the problem is in the image output terminal, the conventional printing system does not provide adequate diagnostic capabilities with respect to isolating problems between the image binarizer or the marking engine because it is difficult, conventionally, to observe the intermediate form of an image as it passes from the image binarizer to the marking engine, thereby hindering the determination of the root cause (source) of image quality problems.
Therefore, it is desirable to provide for the capturing of processed image data within the image output terminal in order to facilitate a more effective determination of the point of failure. By providing for the capturing of processed image data within the image output terminal, processed image data associated with a specific input (document or test image data) captured from a predefined access point in a malfunctioning printing system can be compared with the processed image data associated with the same specific input (document or test image data) captured from the same predefined access point.